Do we need alternative control measures for Zika?

A chemical currently being used as a mosquito control measure against Zika has been associated with reduced motor function in Chinese infants, according to new research from the University of Michigan (MI, USA).

The study focused on organophosphate insecticides, including Naled and Chlorpyrifos, which both affect nerve singling in insects – paralyzing them and triggering respiratory failure. It has previously been suggested that these chemicals may cause adverse affects in humans, for example, laboratory tests have reported low dose organophosphate exposure may inhibit myelination.

However, studies to-date have been occupational, and have not examined the general population, making this new research the first of its kind.

The researchers examined the umbilical cord blood of approximately 240 mothers from 2008–2011, assessing the levels of exposure to 30 different organophosphate insecticides, 5 of which were discovered in over 10% of the samples.

The team then examined the infants after birth, assessing motor function at 6 weeks and 9 months utilising the Peabody Developmental Motor Scales. The group discovered that prenatal exposure to organophosphate insecticides may affect motor development, demonstrating that Naled was associated with a 3–4% decrease in fine motor skills for those in the top 25% of exposure, compared with individuals in the lowest 25%.

In addition, the team reported that exposure to Chlorpyrifos was associated with lower scores for both gross and fine motor skills, specifically a 2–7% decrease. The team also reported that female infants appeared to be more sensitive to the adverse effects when compared with male infants.

First author Monica Silver (University of Michigan) commented: “Motor delays in infancy may be predictive of developmental problems later in childhood. The findings may help inform policy as the debate over use of these chemicals continues.”

Exposure to chemicals has previously been a public health a concern, however, these latest findings highlight that there may be a need to find alternative control measures for mosquito-borne diseases such as Zika.

Senior author John Meeker, from the University of Michigan, concluded: “Zika is a very serious public health threat. This information helps to highlight that the way we go about combating Zika and other vector-borne diseases needs to be thought out more completely in order to minimize other unintended consequences,

“For example, a focus on a more holistic integrated pest management approach may allow for the same or even improved effectiveness in reducing disease while using smaller amounts of these potentially harmful chemicals.”